Many types of electronic systems use DC to DC converters to provide electrical power, particularly portable battery powered devices that require a lower or higher voltage than is directly supplied by the batteries or by other electronic systems requiring multiple voltage levels internally. DC-DC converters process an incoming direct current (DC) voltage and generate an output of a different voltage. DC to DC converters may also regulate the output voltage so that input voltage variations and changing load conditions do not substantially alter the output voltage. A number of different types of DC to DC converters are known, such as buck converters and boost converters.
Many of these are switching regulators, which rapidly switch on and off to transfer packets of energy from an input to an output. The duty cycle of the switching can be controlled to adjust the output voltage, and various circuit configurations are known to provide outputs with higher or lower voltage than the input. Switching regulators are typically very efficient, but have some characteristics to be controlled or minimized such as output voltage ripple. Because of the switching nature of these DC to DC converters, the output voltage may have some ripple despite the use of filters at the output. Stable, or predictable, switching frequency is preferred to simplify selection of such output filter components.
Some examples of prior art systems are U.S. Pat. No. 6,212,079; U.S. Pat. No. 7,202,609; and U.S. Pat. No. 5,764,495.